The invention concerns a method of dephospholipidating whey to separate the lipoproteins out of it and/or decrease its residual fat content by adding calcium to the whey, heating it and keeping it hot to aggregate the lipoproteins, and then centrifuging it.
The lipoproteins or residual fats in the whey are usually detrimental to further processing and to the quality of the final product.
Dephospholipidating whey involves the separation or harvesting of the lipoproteins and may be carried out with both sweet and sour whey.
The lipoproteins or residual fats in the whey consist of small spherules of fat that cannot be separated and of separable fragments of the fat-spherule membranes, which are rich in phospholipids (lecithin, sphingomyelin, cephalin, etc.).
Whey can be dephospholipidated by microfiltration or by a combination of heat treatment and chemical processing.
The whey should be dephospholipidated to at least 50% with no more than 3% of the protein being lost if the advantages attained in processing the whey further are to justify the expense. A whey-protein concentrate with a high level of protein and a low content of fat, for which there is now a high demand in the foodstuffs industry, can be obtained from whey that has been processed in this way. Even dephospholipidation to 50% can lead to a definitely increased output and to longer periods of operation on the part of a downstream ultrafiltration or reverse-osmosis plant, which can be considered one of the greatest economic advantages.
A method of dephospholipidating sweet whey is known from the periodical Le Lait 647 (Jan.-June 1945), pp. 1-19 for example. Dairy whey is treated with approximately 2.22 g of calcium chloride per liter and then heated to approximately 80.degree. C. in a hot-plate heater. The whey is kept hot for 20 seconds and then cooled, precipitating the lipoproteins. The whey is then decanted for 16 hours to separate the lipoproteins, after which the precipitate is added to a centrifuge. The whey itself can be further processed through filters.
This method turns out to have various drawbacks. First, adding the calcium chloride to the whey before it is heated leads to precipitation of calcium in the heater and clogs it up, so that it must be cleaned relatively often, shortening the plant's periods of operation.
Again, since the large quantities of calcium chloride added to the whey before it is heated can severely corrode the heater, the heating plates have to be made of special materials, which are correspondingly expensive.
Furthermore, on an industrial scale the precipitated solids must be decanted subsequent to the heating process in large containers, which is undesirable for reasons of both space and expenditure. The low decantation temperature of 2.degree. C. also necessitates containers with hollow walls and demands a lot of costly energy to chill the large quantities of material. The whey must be heated again for the subsequent filtration, which also consumes energy.
Finally, the high temperature that occurs when the whey is heated and the large quantity of calcium chloride lead to a protein loss of approximately 16.59%, which is excessive for industrial applications.